Upgrade phono stage?

Have an AudioNote M1 phono MM.  It still delivers great music!  I don't know if I should upgrade the phono stage part.  Purchase a stand alone phono stage and run it through the aux inputs?  

Gear, George Wright mono blocks 2a3 (set)
          Audio Note M1 phono MM
          Jager Speakers (Bottlehead)
          Rega P3